Prefibrillar huntingtin oligomers isolated from HD brain potently seed amyloid formation.

Many neurodegenerative diseases are associated with deposits of aggregated protein in the brain. The molecular pathways through which soluble proteins misfold to form amyloids and large protein aggregates often include diverse oligomeric species, only some of which progress to the amyloid state. Here we show that prefibrillar huntingtin (HTT) oligomers, isolated from Huntington's disease (HD) affected human brain samples or mouse models, stimulate polyglutamine amyloid formation.

Comparative study of naturally occurring huntingtin fragments in Drosophila points to exon 1 as the most pathogenic species in Huntington's disease.

Although Huntington's disease is caused by the expansion of a CAG triplet repeat within the context of the 3144-amino acid huntingtin protein (HTT), studies reveal that N-terminal fragments of HTT containing the expanded PolyQ region can be produced by proteolytic processing and/or aberrant splicing. N-terminal HTT fragments are also prevalent in postmortem tissue, and expression of some of these fragments in model organisms can cause pathology. This has led to the hypothesis that N-terminal peptides may be critical modulators of disease pathology, raising the possibility that targeting aberrant splicing or proteolytic processing may present attractive therapeutic targets.

Conformational features of tau fibrils from Alzheimer's disease brain are faithfully propagated by unmodified recombinant protein.

Fibrils composed of tau protein are a pathological hallmark of several neurodegenerative disorders including Alzheimer's disease (AD). Here we show that when recombinant tau protein is seeded with paired helical filaments (PHFs) isolated from AD brain, the amyloid formed shares many of the structural features of AD PHFs. In contrast, tau amyloids formed with heparin as an inducing agent-a common biochemical model of tau misfolding-are structurally distinct from brain-derived PHFs.